In recent years it has been recognized by governmental agencies which are responsible for fire safety that more injuries and deaths occur in a building fire situation due to the inhalation of smoke than by direct burns. Along with this determination of the severe danger posed by smoke, legislatures and building code authorities in many states have enacted new regulations which require dealing with smoke as a prime building design requirement.
One code which deals with this situation and spells out the parameters of smoke control is the North Carolina State Building Code, 1991 Edition, particularly Volume V, relating to Fire Prevention. This code section mandates, under Table 3607, that buildings having floor areas in excess of 10,000 square feet in a single expanse must have their ceilings divided into cell-like areas of from 2,000 to 10,000 square feet to contain and remove smoke from an accidental fire.
The North Carolina Building Code specification requires a "curtain board" to descend from the ceiling for a distance of either four (4) or six (6) feet depending on the height of the ceiling (ranging up to 40 feet) and a fire hazard classification for the building. This "curtain board" joins other "curtain boards" to form a gridwork of rectangular cells on the ceiling; in the approximate center of each cell is an automatically operative ventilator.
In case of a fire, smoke will rise from the source and come into contact with the ceiling. Under prior ceiling conditions, i.e. no "curtain boards", this smoke would spread over the entire ceiling. Under the new regulations, the "curtain boards" in the event of a fire will contain the smoke created in the one or few sections of ceiling where it arose and the cell ventilator, actuated by a smoke detector, will draw that smoke out of the building. Once the smoke is gone, the danger to both occupants and fire fighters is reduced substantially.
Prior to the present invention, the accepted curtain board apparatus and method of installation was relatively expensive, was time consuming and required considerable skill. The prior art material utilized for the "curtain board" was a heavy weight fiber glass fabric which had been resin impregnated to prevent smoke passage. No specification is written for the material characteristics or performance of the "curtain board" in the North Carolina Code. The referred to fabric was used in long lengths and in a width of either four (4) or six (6) feet as per the regulations. This fabric was clamped along an upper longitudinal edge between a piece of angle iron and a piece of flat iron by means of screws and nuts. The lower longitudinal edge of the fabric was sewn with a continuous loop, or pocket, into which was placed an iron rod to keep the curtain hanging vertically down. The angle iron which was clamped to the upper edge of the fabric was in a last step, welded to a joist or girder close to the ceiling level to create one wall of the ceiling dividing cell.
As can be readily seen, the operations employed to make an existing technology curtain board include drilling matching holes in an angle iron and a flat iron piece, piercing a heavy fabric, bolting an assembled angle iron, fabric and flat iron installing the rod and welding the angle iron to a ceiling iron component. In addition, equipment is needed and skill is required for the operations of drilling the holes in the angle iron and flat iron and welding the angle iron to the ceiling framework.
A particular drawback in addition to the labor and skill needed to install the referred to prior art apparatus is due to the operation of welding. If such a system is intended to be installed in an existing building, the welding which occurs at ceiling level will result in some falling sparks. If materials normally housed in the building are not moved or properly covered, the sparks cause a serious fire hazard.
Therefore, it is an objective of the present invention to provide a smoke curtain apparatus and installation method which conforms to building code requirements for smoke containment curtains.
It is a further objective of the invention to provide a curtain apparatus and installation method which is capable of efficient and inexpensive installation.
It is an additional objective of the invention to provide a curtain apparatus and installation method which may be effectuated in an existing, in-use building without danger to materials which may be stored in that building.
These and other objectives will be apparent to those skilled in the art as the details of the disclosure below are understood.